randall L

I'm still having thermal failure upon re-start after driving as little as 10 miles. She doesn't want to re-start about 50% of the time.
When she does start she's shaking like a dog dumping a peach seed.......until I give it a little pedal...then she smooths out & runs fine. Until I turn her off & try to re-start. Back to 50%.

I replaced the CPS last week. New Champion plugs, wires, dizzy, rotor, Bosch injectors, fuel regulator, fuel filter. Saturday afternoon I replaced the ignition coil. I thought that had taken care of the problem. Today I drove her exactly 9 miles & went in a store for maybe 5 minutes. Came out & no start. Until she cooled of a little. Then it was shake city until I hit the footfeed a little.

I have also done the re-fresh on all my connectors.

Anybody got any ideas?

The Rooster

Did you refresh your Grounds??? you can have all those new parts redone conenctions but a bad grounds and makes all the new parts useless... also feel free to click on the link in my sig for Renix trouble shoot...

randall L

Big time refresh on grounds. That's why I'm sad........

The Rooster

Don't be sad we will help you Just going to take sometime

cruiser54

Test your TPS on the engine side, and be sure to do the sensor ground test outlined in the beginning.


RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle body and it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you
have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over.
Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.
AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the square four-wire connector side of the TPS.
If you have ENGINE ISSUES check the flat three-wire connector side of the TPS.
For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 09-22-2012

randall L

Cruiser I'm gonna jump on this as soon as it quits raining. Thanks....

cruiser54

We're gonna have to try some stuff to make sure what it ISN'T. Be patient. None of this is a waste of time. You might wanna shuffle through the write-ups in the link in my signature while it's raining outside.......

randall L

I discovered this morning the TPS on my cherokee is 23 years old. So I'm gonna replace it. That's just the way I am. It may not be my complete problem but I'm putting a new one in.

I'll sleep better.

What's a reasonable cost. Where I am they range from 40 bucks up to well over a $100. Any particular brand?

thanks

The Rooster

Mopar is the brand I would go with... It lasted 23 years why not put another one in to last just as long...

randall L

Well the saga continues. I have thrown a ton of parts at this project. But keep in mind it was intentional with many of them because I am basically restoring this thing.
I was hoping some of these parts would cure the thermal fail issue but as of now it's been to no avail.
This past week I re-freshed ALL of the electrical connections AGAIN. Re-did ALL of the grounds AGAIN.
Also put a new Bosch o2 sens, cat converter, MAP, TPS, oil sender switch, ballast res. & relay, front & rear vacumn harness, another AF cause the old one was getting some blow back from bad harnesses. The new TPS is a MOPAR & test fine. Doesn't have 100 miles on it. Same with the CPS.
I suppose about all that's left to throw is the coolant temp sensor(when I locate the right one) fuel pump & sending unit. We did a fuel pressure test last Monday & it does not appear I have injector leak down. Fuel regulator is new. Filter is new.
I let the fuel tank get almost empty & put 2 can of seafoam in & 17 gallons of Chevron premium & got stranded 4 times this weekend alone.
That is getting really old.
Dang if I know what else to mess with & after all this she's getting really close to goin up in smoke.........

The Rooster

What was your fuel pressure when you tested it?

captainwoot

Not sure if it is any help (i havn't worked on a renix in a long time) , Cruiser and Rooster can chime in..isn't there a ignition module of sorts under the coil..that would occasionaly fail like that???
And I am as curious as Rooster ..fuel pressure?..
Good luck

randall L

Fuel pressure at the rail was 30psi. & when I pulled the vac. hose off of the regulator it went up to 38psi.

I did a leak down test right after that. The pressure on shutdown was 30psi.
& I checked it 30 minutes later & it had dropped 15psi.

That's within specs isn't it?

Also discovered yesterday afternoon she won't downshift AT ALL. Unless it's just slowing down for a normal stop. If you had to pass another vehicle........good luck......better have plenty of room. She just accelerates without a down shift.
Gonna go back & re-check the TPS adjustment & then look at the TCU.

Still on meltdown........

freegdr

Adjust detent cable lately

cruiser54

Check both sides of the tPS.